The present invention is directed to a novel drive system for a palletized conveyor. More particularly, the present invention is directed to a modular friction drive system for a palletized conveyor.
A palletized conveyor of the type relevant to the present invention generally includes a number of carriers (pallets) that glide over a series of free-turning rollers. The pallets are provided to transport various articles to a downstream position. Typically, there are a plurality of pallets associated with a single conveyor.
In a palletized conveyor system like that described above, neither the individual pallets or the underlying rollers are driven. Rather, the rollers turn freely in bearings or other similar supports. The pallets then move along the length of the conveyor by gliding over top of the rollers. The pallets are usually restrained against transverse movement by rails or a similar barrier.
Because neither the pallets themselves nor the rollers are driven, an external motive force must be applied to the pallets in order to move the pallets along the conveyor. This may be accomplished in several ways according to the known art, such as, for example, by means of an endless chain or belt located adjacent to the conveyor. In such an embodiment, the chain or belt may be equipped with a number of engaging cogs that contact the pallets and urge them along the conveyor as the chain or belt rotates. Alternatively, a plurality of driving wheels may be stationed along the length of the conveyor and positioned to make contact with a portion of each pallet as it traverses the conveyor. Such driving wheels may be individually driven or may be collectively driven—such as by a belt or chain coupled to a single drive motor.
Still other known drive systems make use of a single, or small number of drivers near the loading portion of the conveyor only. These drivers act to propel the pallets toward the opposite end of the conveyor. However, because palletized conveyors are often of considerable length, the drivers of such a system typically must impart a significant force to the pallets in order to provide enough velocity to propel the pallets along the entire length of the conveyor. Applying such an accelerating force, unfortunately, also causes an abrupt movement of the pallets and may upset the loads carried thereby. Further, the pallets are typically launched along the conveyor with significant gaps therebetween. This of course, is an inefficient use of conveyor space and also makes possible collisions between pallets that, for one reason or another, move along the conveyor at different velocities.
Often, these known systems further require the use of complex pivoting or rotating assemblies to ensure proper contact of the driving element(s) with the pallets. Such assemblies invite unnecessary maintenance and repair.
As can be gleaned from the foregoing discussion, it is also desirable to keep the individual pallets in contact with one another as they travel down the conveyor. This is advantageous for several reasons: such as to maximize transport efficiency and to avoid pallet collisions. It is also desirable to minimize the complexity and space consumed by the pallet drive system.
Known palletized conveyors and palletized conveyor drive systems are often deficient in one or more ways. For example, locating a drive chain or drive belt along the entire length of the conveyor consumes a great amount of space, as does locating a plurality of driven wheels along the length of the conveyor. Additionally, employing a plurality of individual drive wheels also makes maintaining contact between pallets quite difficult. Such systems also are not typically readily adaptable to changes in conveyor and/or pallet design, or to conveyor operation. Further, employing a single drive mechanism at one end of a palletized conveyor results in an inefficient use of conveyor space and facilitates undesirable pallet collisions.
Consequently, there is a need for a simplified and adaptable palletized conveyor drive system that meets the aforementioned needs/desires. A modular friction drive system of the present invention satisfies this need.